<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>显示当前时间</title>
</head>

<body>
    <p>在页面显示一个时钟</p>
    <p id="demo"></p>
    <script>
        var myVar = setInterval(function () { myTimer() }, 1000);
        function myTimer() {
            var d = new Date();
            var t = d.toLocaleTimeString();
            document.getElementById("demo").innerHTML = t;
        }
    </script>
</body>

</html>